En Report (Scie) F&B

Report Number 589 Low tide survey of The Wash Special Protection Area Final report of the winter 2002-2003 shorebird survey English Nature Research Reports working today for nature tomorrow English Nature Research Reports Number 589 Low tide survey of The Wash Special Protection Area Final report of the winter 2002-2003 shorebird survey Mick Yates1, Angus Garbutt1, Ed Rispin2 and Nigel Brown1. 1 CEH Monks Wood 2 CEH Dorset You may reproduce as many additional copies of this report as you like, provided such copies stipulate that copyright remains with English Nature, Northminster House, Peterborough PE1 1UA ISSN 0967-876X © Copyright English Nature 2004 Intellectual Property Rights Confidentiality Statement ‘In accordance with our normal practice, this report is for use only of the party to whom it is addressed, and no responsibility is accepted to any third party for the whole or any part of its contents. Neither the whole nor any part of this report or any reference thereto may be included in any published document, circular or statement, nor published of referred to in any way without our written approval of the form and context in which it may appear.’ Acknowledgements We gratefully acknowledge the permission given by the Commanding Officers of RAF Wainfleet and RAF Holbeach to access the RAF ranges on the Wash and to landowners for allowing us to cross their land to access the intertidal flats. It is a pleasure to acknowledge the staff of Eastern Sea Fisheries Joint Committee for providing safe access to the outer banks and both Essex and Suffolk Water Company and Black and Veatch Consulting Ltd (formerly Binnie, Black and Veatch) for allowing us to use data acquired as part of the study to monitor the Denver Licence Variation. Summary This report describes the methods used and the results of low tide surveys of shorebirds and wildfowl feeding and roosting on the intertidal mud- and sand-flats of the Wash Special Protection Area (SPA) made during winter 2002-03. The entire area of intertidal mud- and sand-flats was surveyed at low tide and the numbers and distribution of feeding waders (Charadrii) and shelduck Tadorna tadorna and roosting wildfowl, sea ducks and waders were recorded and mapped. This is the first time any such survey has included all the intertidal mud- and sand-flat areas, previous ones having been confined to either the inner banks alone, or to the inner banks plus parts of the outer banks of the Wash. Of the feeding birds, knot Calidris canutus were the most abundant. All species fed on both the inner and outer banks of the Wash apart from shelduck, ringed plover Charadrius hiaticula and black-tailed godwit Limosa limosa which occurred only on the inner banks. Golden plover Pluvialis apricaria was the most abundant wader roosting on the intertidal flats, while brent goose Branta bernicla spp bernicla was the most abundant of the wildfowl species and eider Somateria mollissima the most abundant sea-duck. All of the roosting birds were recorded on inner bank areas with the exception of a small number of eider that occurred on the outer banks. Total numbers recorded in the low tide survey were compared with the WeBS high tide counts of the Wash made over the same time period as the low tide survey. Of the feeding birds, the numbers of shelduck, knot, dunlin, curlew and redshank recorded at low tide were very similar to those recorded at high tide. Fewer oystercatchers were recorded at high tide than at low tide while, in contrast, more ringed plover, grey plover, sanderling, black- and bar-tailed godwits and turnstone were seen at high than at low tide though the discrepancies in numbers of these species could be accounted for by anecdotal evidence with the exception of black-tailed godwit and grey plover. The correspondence between the numbers of roosting wildfowl, sea ducks and waders recorded at low tide and in the WeBS counts was expected to be poorer because not all species feed or roost within the area covered by either method. Even so there were good correspondences in the numbers for wigeon Anas penelope, mallard Anas platyrhynchos, eider and golden plover. Overall, the excellent correspondence between the low tide and the WeBS counts of the majority of the feeding wader species is particularly note worthy. It is very reassuring, given the size of the Wash and the differences between the methodologies, that the two estimates of the numbers using the Wash were so similar. Comparisons were made between the current survey and four low tide surveys made of the inner banks of the Wash over the period 1985-1992 for shelduck and the seven most numerous waders that fed on the intertidal areas. The numbers of oystercatchers Haematopus ostralegus, grey plover Pluvialis squartarola and knot were all lower in the current survey than they had been in any of the previous ones while those of the remaining species were within the ranges previously recorded. No species was more numerous in the current survey than it had been in any of the previous ones. At a Wash-wide scale, the distribution of the birds in the current survey showed little change from that in previous surveys. Indeed the most notable feature was the constancy in distribution. At a more local scale (1 km) some changes were apparent. These were probably related to variations in abundance and distribution of the birds’ invertebrate prey and to the normal process of sediment accretion at upper levels of the shore. Comparisons were also made between the low tide surveys of the inner bank intertidal areas of the Wash as well as those adjacent to the river Great Ouse outfall that have been made from 1997 and both the WeBS Wash counts and UK index over the same period. The purpose of these comparisons was to put the annual changes in numbers recorded in these low tide surveys into a whole Wash and national perspective. Changes in shelduck, oystercatchers and knot on the inner banks of the Wash, in the whole Wash and nationally were generally rather similar while the pattern of change in the remaining five wader species on the inner banks of the Wash differed either from those in the whole Wash or nationally or both. Generally the pattern of annual change in the Great Ouse study area, the whole Wash and nationally was similar for oystercatcher, grey plover, knot, dunlin, curlew and, to a lesser extent, redshank. Changes in shelduck and bar-tailed godwit numbers on the other hand varied more. This suggests that annual variations in numbers of some, but not all, species in the Great Ouse area is indicative of variations in the whole Wash and in turn in national numbers. There was evidence that the Great Ouse area is a preferred feeding area of bar-tailed godwit. Contents Acknowledgements Summary 1. Introduction..................................................................................................................13 2. Methods........................................................................................................................13 2.1 Survey methods................................................................................................13 2.2 Areas surveyed.................................................................................................14 2.3 Sequence in which areas were surveyed..........................................................14 2.4 Data transcription and collation.......................................................................15 3. Results and discussion.................................................................................................15 3.1 Bird numbers recorded in the 2002-03 low tide survey of the Wash ..............16 3.1.1 Feeding shelduck and waders ..............................................................16 3.1.2 Roosting wildfowl, sea-ducks and waders...........................................16 3.1.3 Comparisons with WeBS counts data..................................................17 3.2 Bird distribution in the 2002-03 survey...........................................................18 3.2.1 Feeding shelduck and waders ..............................................................18 3.2.2 Roosting wildfowl, sea-ducks and waders...........................................20 3.3 Comparisons with previous low tide surveys of the Wash..............................20 3.3.1 Changes in total numbers on the inner banks ......................................21 3.3.2 Changes in distribution........................................................................22 3.3.3 The Great Ouse study area surveys......................................................23 4. General comments and conclusions.............................................................................24 5. References....................................................................................................................25 Appendix 1...............................................................................................................................57 List of tables Table 2.1 The chronological sequence in which intertidal areas were surveyed. Refer to Figure 2.1 for the location of the areas. ...........................................................15 Table 3.1 The numbers of feeding shelduck and waders recorded in the 2002-03 low tide survey of the Wash. (Number in parenthesis is the low tide count expressed as percentage of the WeBS total) .........................................................................16 Table 3.2 The numbers of roosting wildfowl, sea ducks and waders

Load more